The transmission slips, so it will likely need a complete rebuild before being put back into service.
The TH350C is much less common than the standard TH350 because it uses a lock-up torque converter, and this is the desirable unicase version. These are becoming increasingly difficult to find, especially for restorations or anyone wanting an original TH350C rather than converting to another transmission.
Features:
GM TH350C (Turbo Hydramatic 350C)
Rare lock-up ("C") model
Unicase design
Good rebuildable core
Sold AS-IS
Great for restoration, rebuild, or spare parts